The present invention is related to electric power generation systems (EPGSs).
In aircraft applications, electric power generation is derived, in large part, from mechanical power supplied by the aircraft's engines, which is converted to alternating current (AC) electric power by a generator. Variations in aircraft engine speed result in variation in the output voltage and frequency produced by the generator. However, some loads are sensitive to variations in voltage and frequency, and therefore most generators employed on modern-day aircraft provide regulated output voltage and either a constant output frequency or a variable frequency within a defined range that is acceptable to attached loads. For example, constant frequency generators use mechanical couplings to provide a constant-frequency AC output despite variations in engine speed. However, the mechanical couplings add to the cost and weight of the generator. Variable-frequency generators are an alternative to constant frequency generators, but must still be capable of providing an AC output within a well-defined range (e.g., 350 Hz-800 Hz). This requirement also adds to the weight and cost of variable-frequency generators. Regulating generator output voltage is done using generator field control or power conversion electronics, both of which add cost and weight to the power generation system.
A less expensive alternative to regulated voltage, constant-frequency and variable-frequency generators is a wild-source generator that provides a variable-voltage, variable frequency AC output, typically with output frequency ranges greater than that seen in variable-voltage generators. Traditionally, wild-source generators have not found applicability in aircraft applications because of their inability to provide the type of high-quality power (i.e., stable frequency) required by most loads on the aircraft.